very low temperature measurement

Discussion in 'The Projects Forum' started by Omega, Apr 20, 2009.

  1. Omega

    Thread Starter Member

    Feb 23, 2009
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    Hi every one I have to design electric measurement system to measure low temperature (mili to micro kelvin) any helpfull ideas?
    ω
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    What is the substance you are trying to measure the temperature of?
    Liquid helium is the coldest I know, that has a temperature of about 4.2 Kelvin.

    Greetings,
    Bertus
     
  3. Omega

    Thread Starter Member

    Feb 23, 2009
    15
    0
    there is no specific material but I am trying to learn how I can measure this low temperature using electronics
     
  4. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    Measuring those low twmperatures is pretty hard to do.
    Some materials will become superconducting, so you can not measure the resistance anymore.
    An other practical problem : isolation material like a lot of plastics will break when moved because they have become very hard.

    Greetings,
    Bertus
     
  5. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,536
    This sounds like a physics problem. At that temperature range lots of really odd and exotic things happen, such as Bose-Einstein Condensates. I don't have a clue myself, a black body measurement perhaps?
     
    Last edited: Apr 20, 2009
  6. Skeebopstop

    Active Member

    Jan 9, 2009
    358
    3
    I recently read about dark matter detectors. One of the two competing methods is to use NTC thermistors to measure for temperature fluxuations at temperatures of millikelvins. I do not know if they are measuring for 'realistic' temperatures, versus simple fluxuation anamolies due to an inbound particle collision. Regardless it is similar to what you seem to be after.

    Read up on them, maybe they hold the answers.
     
  7. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
    2,039
    287
    I would imagine that noise would be the easiest to measure with fairly common equipment.

    eric
     
  8. leftyretro

    Active Member

    Nov 25, 2008
    394
    2
    Well there is a big difference between how one would measure temperatures with millikelvins resolution and how one would read absolute millikelvins range temperatures. Which one are you inquiring about?

    Lefty
     
  9. Omega

    Thread Starter Member

    Feb 23, 2009
    15
    0
    I would like to measure absolute values of temperatures in the range of milikelvins down to microkelvins. I think NTC thermistors measures temperatures down to 10 Kelvin not less than that
     
  10. Skeebopstop

    Active Member

    Jan 9, 2009
    358
    3
    The NTCs in use in the dark matter detectors operate at millikelvins. I cannot speak for their absolute measurement properties.
     
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